


know better and learn faster

by chime



Series: i need you to be better than me [1]
Category: Kamen Rider Build
Genre: Gen
Language: English
Status: Completed
Published: 2018-06-11
Updated: 2018-06-11
Packaged: 2019-05-20 20:09:33
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 902
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14901167
Author URL: https://archiveofourown.org/users/chime/pseuds/chime
Summary: Katsuragi doesn't go away, not completely.[episode 39 spoilers]





	know better and learn faster

**Author's Note:**

> i thought the idea of sento and katsuragi coexisting was kind of interesting, i embellished some aspects of how their communication works just so it would actually be easy to read. also there is some ryusen implication but it didn't seem relevant enough to tag it
> 
> thanks for reading!

Sento feels something is off when he’s working on a side project - not for the driver, not something from Katsuragi or his father’s files. Something from him.

 

The experiment is going well, up until he goes to connect some wires and he feels a ripple of displeasure, like someone clearing their throat.

 

He frowns at his handiwork. He was sure he had done everything correctly, but he does sometimes get so into his work he doesn’t properly record every single step -

 

And again, that foreign feeling, this time disgust. _You missed a step, it will never work that way._

 

Sento’s mouth forms a thin line. He realizes his mistake, now, without even really knowing. And, more troubling than that, is the realization that this feeling - this voice, but not a voice - is somewhat familiar.

 

“Katsuragi?” He says, just loud enough to be heard. He’s not quite sure how this works yet and wants to make sure this initial communication goes smoothly.

 

_Obviously._

 

Sento looks around the lab. Kazumin and Sawa are out, and Banjou and Misora are leaving him alone upstairs. Gentoku is… Somewhere. He can speak freely. “How is this possible? I thought we… Integrated.”

 

_You still don’t have my memories, right? That should have been your first clue._

 

“Still,” Sento says, “This isn’t how it was before.”

 

 _No._ Katsuragi seems frustrated. _That would be too easy._

 

Sento sighs, putting down his tools and sitting back in his chair. “Why didn’t you say something earlier?” It had been some time since he took over again.

 

_You seemed busy._

 

Sento guesses it’s more than that - it took time to get here. Hesitantly, Sento says, “What do you want to do about this?”

 

There is a pause before Sento gets a response. _You said you’d show me, didn’t you?_

 

Sento laughs, surprised. “Well,” He says, and does a mock salute, “It would be my pleasure.”

 

\----

 

Sento and Katsuragi are pretty similar, to both of their annoyance. (Sento wonders, briefly, if he should call him Takumi. To which Katsuragi replied, _We are not friends._ So he doesn’t.)

 

It’s sort of fun, having him around. Katsuragi gives him advice (asked for or not) on his projects, and Sento has someone to tease when no one else is around. He thinks it’s kind of like being roommates with your coworker, in a weird way.

 

Still, Sento doesn’t _trust_ him. They don’t talk about Katsuragi taking control again.

 

They don’t talk about important things at all, really. That’s another thing they have in common, Sento guesses.

 

Sento’s life would definitely be easier if Katsuragi had just disappeared again. No spacing out, no mumbling to himself, no (or, well, less) worried looks from his friends.

 

He has to wonder how long he can keep hiding Katsuragi from everyone.

 

\----

 

Sento is standing in the kitchen, having a minor argument with Katsuragi about what to make for dinner, since it’s his turn.

 

Katsuragi cannot cook. This is unsurprising to Sento, who had to bite back a comment about being a “mama’s boy”, because that’s another thing they do not talk about. Still, Katsuragi likes to _think_ he knows what he’s talking about, since he’s Sento, right, and Sento can cook.

 

“You alright, Sento?” Banjou says, suddenly at his side. Banjou’s been keeping an eye on him since Katsuragi “left”, which mostly means sticking to him like glue. Sento can’t complain.

 

Katsuragi hates it, hates Banjou, hates the way Sento feels warm and safe whenever Banjou looks at him like he almost can’t believe he’s there. What a killjoy.

 

“Yeah,” Sento says, feeling his face soften. He’s so far gone it’s almost embarrassing. “What do you want for dinner? And don’t say cup noodles.”

 

“Misora was talking about pasta earlier. I think we’ve got stuff for that?” Supplies are getting kind of scarce, even with Sawa’s almost magic ability to find groceries.

 

Sento nods. “Tell the others food’ll be ready soon.”

 

Banjou pauses, like he wants to say something. Then he nods, too, and heads out.

 

_What do you see in him?_

 

Sento sighs. He knew they’d have this conversation sometime. “You’re not really one to talk, are you?”

 

 _I would appreciate it if you would stop slandering me._ Sento almost laughs imagining his expression.

 

Sento shrugs. He doesn’t like being candid, even with himself. “You don’t know him. I wouldn’t be me without him.”

 

Katsuragi goes quiet for a while after that, mulling it over. Sento appreciates the silence, at least.

 

\----

 

“Who are you talking to?”

 

Sento looks up, to where Misora is standing at the bottom of the stairs.

 

“Myself,” Sento offers.

 

Misora frowns. “You’ve been talking to Katsuragi, haven’t you?”

 

“Ah,” Sento says, turning to fully face her. “You knew?”

 

“I figured it out,” Misora says. She looks sad. “You’ve been distracted… Is he still with you? Right now?”

 

Sento nods. Katsuragi is silent, wary.

 

“I don’t trust him,” Misora says, plain. Sento loves her for that. “He hurt people. He wants to hurt Banjou.”

 

“I know,” Sento says. “I won’t let him.”

 

“Okay,” Misora says, taking a deep breath. She doesn’t look completely convinced. “You should tell the others.”

 

Katsuragi bristles. Sento says, “I know. Right now?”

 

“When you’re ready.” Misora says, “But I _will_ bug you about it.”

 

Sento snorts. “Of course.”

 

“Come eat.” Misora says, and Sento guesses the matter is settled for now.

 

“Thanks, Misora,” Sento says, and they walk up the stairs together.


End file.
